I've found that emphasising performance or ease of implementation when selecting data [storage] representations generally forces the model/real-world mismatch up into the software layer

.....plus in the hierarchical/network view of the world (tempted to say NoSQL) :-

a) that design will only be performant for that particular view of your model and

b) Wolpert's No Free Lunch theorems tell us that that performance is wrought at the expense of sub optimal performance of some other part of the system. So you are effectively taking a punt on which parts of the application sub-optimal performance can be tolerated.